TI Designs 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives TI Designs Design Features TI Designs provide the foundation that you need including methodology, testing and design files to quickly evaluate and customize the system. TI Designs help you accelerate your time to market. • Design Resources TIDA-00173 Tool Folder Containing Design Files UCC28711 LMS33460 Product Folder Product Folder • • • • • ASK Our E2E Experts WEBENCH® Calculator Tools • • • 50-W main power supply with isolated and nonisolated voltage rails to power control electronics within variable speed drive Can operate with dc (1200 V dc max) or ac input (380–690 V ac) < 5% load and line regulation Input UV/OV, output overload, and sc protection Protection against loss of feedback Lower-cost solution using UCC28711 through primary side regulation – Eliminates feedback loop – Use of 1000-V rated MOSFET Quasi-resonant mode controller improves EMI –10°C to 65°C max operating temperature range Designed to comply with IEC 61800-5 Featured Applications • • • • • Variable Speed ac and dc Drives Industrial Inverters Solar Inverters UPS Systems Servo Drives 90 89 88 Efficiency (%) 87 86 85 84 83 82 81 80 300 400 500 600 700 800 900 1000 1100 1200 1300 Vin (VDC) D001 An IMPORTANT NOTICE at the end of this TI reference design addresses authorized use, intellectual property matters and other important disclaimers and information. All trademarks are the property of their respective owners. TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives Copyright © 2014, Texas Instruments Incorporated 1 System Description 1 www.ti.com System Description Variable-speed drive (VSD) consists of a power section, controller, user IO, display, and communication blocks. The power section contains a rectifier, a dc link, inrush current limiting, and an insulated-gate bipolar transistor (IGBT) based inverter. VSD can be based on single or dual controller architecture. When using single controller architecture, the same processor controls generation of pulse-width modulation (PWM), motion control, IO interface, and communication. When dual controller architecture is used, PWM and motion control have a dedicated controller and the other controller is used for application control. The main power supply, either powered directly from ac mains or from dc links, is used to generate multiple voltage rails. Multiple voltage rails are required for the operation of all the control electronics in the drive. The traditional way of implementing the main power supply is to use flyback converters with PWM controller ICs, such as UCC3842, UCC3843, or UCC3844. Due to a regenerative action from the motor, the voltage rating of the MOSFET used in the flyback converter has to be > 1.5 kV, depending upon the voltage rating of the drive. Opto-couplers are used for isolated feedback and to regulate the output voltage. In case of failure of components used in the feedback path, the output may reach a dangerously high level, which would damage all the electronic components. Use of controllers like the UCC3842 device presents other challenges, for example, limiting the power during short circuit across wide input-voltage range and power dissipation in the resistors used in startup circuit. The primary objective of this reference design is to create a power supply with reduced BOM cost and a reusable design for drives operating at both 400-V and 690-V inputs. Other benefits include: • Topology to replace single high-voltage FET with two low-cost FETs • Constant uniform power limit throughout the input range • Reduced BOM cost by using UCC28711 through primary side regulation, thus eliminating isolated secondary feedback • Protection against component failure in the feedback path This reference design provides isolated 24 V, 16 V, –16 V, and 6 V outputs to power the control electronics in variable speed drives. The power supply can be either powered directly from 3-phase ac mains or can be powered from dc-link voltage. This design uses quasi-resonant flyback topology and is rated for 50-W output. The line and load regulation of the power supply is designed to be within 5%. The power supply is designed to meet the clearance, creepage, and isolation test voltages as per IEC61800-5 requirements. DC Link Inverter M 3 phase input 200-240 Vac ± 10% 380-480 Vac ± 10% 525-600 Vac ± 10% 525-690 Vac ± 10% Maximum DC Bus voltage range 200-240 Vac -> 410 Vdc 380-480 Vac -> 820 Vdc 525-600 Vac -> 975 Vdc 525-690 Vac -> 1130 Vdc DC-DC FLYBACK CONVERTER +24 V +16 V GND1 ±16 V +6 V GND2 Figure 1. Variable-Speed Drive Topology 2 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback Copyright © 2014, Texas Instruments Incorporated System Description www.ti.com 3W HMI Interface (LCD/Switches) Analog and Digital IO 8W Isolator Inter Processor Communication Motor Controller (With Isolated Motor Current and Voltage Measurement) Application Controller RS485 INTERFACE GND2 +16V -16V GND1 4.5W FAN 5W Encoder Interface 24V 2W Option Card Communication 24V 8W Option Card Communication 6V GND1 7W Analog/Digital IO Resolver Interface 5W Safe Option 2W 5W 0.5W Profibus Profinet EtherCat PowerLink Etc. Figure 2. Drive Control Architecture with Typical Power Consumption 1.1 Requirements of Power Supply The requirements of the main power supply to be used in drive applications are as follows: • 400 V dc to 1200 V dc input • 50-W output power • > 40 kHz switching frequency • Quasi-resonant mode controller • 80% expected efficiency • < 200 mV secondary ripple voltage • < 5% load and line regulation • Input UV/OV shutdown • Output overload shutdown with power limit • Can be powered from ac mains or from dc link • Isolated measurement of dc link voltage (input) through indirect technique • Detection of single phase scenario through dc link measurement • EMC filter and surge protection required • 65°C max ambient temperature • Clearance and creepage as per IEC 61800-5-2 TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives Copyright © 2014, Texas Instruments Incorporated 3 Design Features 2 www.ti.com Design Features This power-supply design is intended to replace the high-cost, high-voltage MOSFET with a low-cost, lowvoltage MOSFET along with omission of feedback components. Also, the power supply is designed to operate across a wide input range, which will suit drives operating from 400 V and 690 V ac inputs. The power supply includes the following protection features: • Output overvoltage fault • Input undervoltage fault • Internal overtemperature fault • Primary overcurrent fault 2.1 Topology Selection Flyback topology is the most widely used switch mode power supply (SMPS) topology in most of the variable speed drives. The power ratings are below 150 W and SMPS topologies only require a single magnetic element; therefore, serves the purpose of isolation, step-up or step-down conversions, and acts as an energy storage element. The attractive feature of using this topology is that no output inductors are required. Other advantages include easy creation of multiple output voltages, very low component count, and low cost. With flyback converters using a single switching element, an expensive 1500 V (or more expensive for 690 V ac rated drives) MOSFET must be used to support the transformer flyback voltage on top of the high-input voltage and voltage generated through regenerative action. Figure 3. Flyback Controller with Single and Dual MOSFET Switch In the case of cascode flyback converter (see Figure 3), MOSFET Q1 with low gate charge Qg, is connected in series with MOSFET Q2. In this case, the Q1 is driven directly from the PWM controller. With cascode configuration, it is possible to distribute the voltage stress across two devices, thus resulting in an overall voltage rating equal to the sum of the individual MOSFET voltages. Using the cascode technique with a low-cost 900-V MOSFET results in an overall voltage rating of 1800 V, which allows supply operation over the desired wide input-voltage range of 350 to 720 V ac. This simple circuit requires a limited control change, which is attained from the original TVS supplied from input supply. 4 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback Copyright © 2014, Texas Instruments Incorporated Design Features www.ti.com 2.2 2.2.1 Cascode Operation Turn ON Sequence When the gate-source voltage of MOSFET Q1 (Vgs1) is greater than its gate threshold voltage, Vth1, the Q1 fully enhances and is turned ON. As soon as the Q1 turns ON, the source of Q2 is connected to ground through Q1, which makes the zener voltage apply across the gate source of Q2, and it gets turned ON. Next, the cascode converter reaches the conduction state; then the current starts to flow through the primary winding of the flyback transformer and the two switches (Q1 and Q2). The voltage drop across both MOSFETs is equal to their on-state voltage drops. 2.2.2 Turn OFF Sequence When the gate-source voltage Vgs1 is less than its gate threshold voltage Vth1, MOSFET Q1 is turned OFF. The current takes a path through the drain to the source capacitance of Q1. Now the drain source voltage Vds1 across Q1 starts to increase. At this time, the potential source terminal of HV MOSFET Q2 starts to build up. As the potential source terminal of Q2 builds up, the gate-source voltage Vgs2 of the MOSFET is reduced. When Q2 reaches its gate threshold voltage Vth2, the Q2 is turned OFF. 800 V(VDS2) V(VDS1) 700 600 Voltage (V) 500 400 300 200 100 0 -100 0 200P 300P 400P 500P Time (s) 600P 700P 800P 900P 1m 200P 300P 400P 500P Time (s) 600P 700P 800P 900P 1m 100P 900 V(VDS2) V(VDS1) 800 700 Voltage (V) 600 500 400 300 200 100 0 -100 0 100P Figure 4. VDS Voltage of MOSFETs During Low VIN and High VIN TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives Copyright © 2014, Texas Instruments Incorporated 5 Design Features 2.3 www.ti.com Design Requirements To translate the Requirements of Power Supply to the sub-system level, the requirements of the PWM controller, MOSFETs, and transformer are listed in Section 2.3.1 through Section 2.3.3. 2.3.1 PWM Controller Accurate voltage and constant current regulation primary-side feedback Primary-side feedback, eliminates the need for opto-coupler feedback circuits Discontinuous conduction mode with valley switching to minimize switching losses Protection functions • Output and input overvoltage fault • Input undervoltage fault • Internal over-temperature fault • Primary overcurrent fault • Loss of feedback signal 2.3.2 Power MOSFETs • • 2.3.3 Transformer Specifications (as per IEC61800-5-1) • • • • • • • 6 Each MOSFET should have a rated VDS ≥ 1000 V to support 1200 V dc input Should support 1.5 A (minimum) drain current Four isolated outputs: – Vout1 = 24 V, 45 W – Vout2 = ±16 V, 4.5 W – Vout3 = 6 V, 0.5 W – Vaux = 16 V, 15 W (only when Vout1 is de-rated accordingly) Switching frequency = 50 kHz Primary to secondary isolation = 7.4 kV for 1.2, 50-μs impulse voltage Type test voltage: – Primary to Secondary = 3.6 kVRMS – Secondary 1 to Secondary 2 = 1.8 kVRMS – Secondary 1 to Secondary 3 = 1.8 kVRMS – Secondary 2 to Secondary 3 = 1.8 kVRMS Spacings: – Primary to Secondary clearance = 8 mm – Secondary 1 to Secondary 2 clearance = 5.5 mm – Secondary 2 to Secondary 3 clearance = 5.5 mm – Secondary 3 to Secondary 4 clearance = 5.5 mm – Creepage distance = 9.2 mm Functional isolation primary and secondaries = 2 kV dc dc isolation between secondaries = 2 kV dc 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback Copyright © 2014, Texas Instruments Incorporated Design Features www.ti.com 45W 24V 16V Primary 4.5W GND AUX Winding 15W -16V 6V_COMM 0.5W GND1 Figure 5. Transformer Configuration TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives Copyright © 2014, Texas Instruments Incorporated 7 Block Diagram 3 www.ti.com Block Diagram The simplified implementation diagram is shown in Figure 6. The transformer has three secondary windings (two isolated and one nonisolated). The auxiliary winding can be loaded up to 15 W, provided that the output from the main secondary is reduced from 45 W to 30 W. The power train consists of two MOSFETs in cascode connection. In primary-side control, the output voltage is sensed on the auxiliary winding during the transfer of transformer energy to the secondary. ETD29 Figure 6. Simplified Diagram of the Solution To achieve an accurate representation of the secondary output voltage on the auxiliary winding, the discriminator inside the IC reliably blocks the leakage inductance reset and ringing. The discriminator continuously samples the auxiliary voltage during the down slope after the ringing is diminished and also captures the error signal when the secondary winding reaches zero current. The internal reference on VS is 4.05 V. Temperature compensation on the VS reference voltage of –0.8 mV/°C offsets the change in the output rectifier forward voltage with temperature. The feedback resistor divider is selected as outlined in the VS pin description (see Section 5.2.7). 8 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback Copyright © 2014, Texas Instruments Incorporated Block Diagram www.ti.com tLK_RESET tSMPL Vs VS Ring (p-p) tDM Time Figure 7. Aux Waveform — Sampling TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives Copyright © 2014, Texas Instruments Incorporated 9 Block Diagram 3.1 www.ti.com Primary-Side Current Regulation When the average output current reaches the regulation reference in the current control block, the controller operates in frequency modulation mode to control the output current at any output voltage at or below the voltage regulation target — as long as the auxiliary winding can keep VDD above the UVLO turn-off threshold. VOCV 5.25 5 4.75 Output Voltage (V) 4 ±5 tSMPL 3 2 1 IOCC Output Current Figure 8. Power Limit 4 Highlighted Products This reference design features the following devices, which were selected based on their specifications. • UCC28711 – Constant-Voltage, Constant-Current PWM Controller with Primary-Side Regulation • LMS33460 – 3-V Undervoltage Detector For more information on each of these devices, see the respective product folders at www.TI.com or click on the links for the product folders on the first page of this reference design. 10 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback Copyright © 2014, Texas Instruments Incorporated Component Selection and Circuit Design www.ti.com 5 Component Selection and Circuit Design 5.1 Component Selection The UCC28711 and LMS33460 components are selected based on their specifications. 5.1.1 UCC28711 The UCC28700 device is a flyback power-supply controller, which provides accurate voltage and constant current regulation with primary-side feedback, thus eliminating the need for opto-coupler feedback circuits. The controller operates in discontinuous conduction mode with valley switching to minimize switching losses. The modulation scheme is a combination of frequency and primary peak-current modulation to provide high conversion efficiency across the load range. The controller has a maximum switching frequency of 130 kHz and allows for a shut-down operation using the NTC pin. 5.1.2 LMS33460 The LMS33460 device is an undervoltage detector with a 3.0-V threshold and extremely low power consumption. The LMS33460 device is specifically designed to accurately monitor power supplies. This IC generates an active output whenever the input voltage drops below 3.0 Volts. This device uses a precision on-chip voltage reference and a comparator to measure the input voltage. Built-in hysteresis helps prevent erratic operation in the presence of noise. 5.2 Circuit Design The ac input is full-wave rectified by diodes D1 through D12. Resistors R1 through R3 provide in-rush current limiting and protection against catastrophic circuit failure. Capacitors C6 through C8 are used to filter the rectified ac supply. Three capacitors of 47 µF, 450 V are connected in a series to support more than 1200 V, although 450 V is the maximum value available on the market. To avoid an unbalanced voltage spread between capacitors, resistances are connected in parallel with each capacitor. 5.2.1 Input Diode Bridge Equation 1 and Equation 2 determine the selected input bridge. P 50 Pinmax = out = = 62.5 W h 0.8 I inrms = (1) Pinmax 62.5 = = 0.182 A 1.732 ´ Vac min ´ cos Æ 1.732 ´ 330 ´ 0.6 where • cosø is the power factor, which is assumed to be 0.6 (2) Equation 3 determines the minimum voltage rating of the rectifier. VdcMIN = (VacMAX × 1.414) + (0.15 × VacMAX × 1.4141) = (480 × 1.414) + (0.15 × 480 × 1.414) = 780 V (3) Considering the raise in dc bus voltage due to regenerative action, two diodes of 1000 V with 1-A rating are used for the 3-phase bridge rectifier. TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives Copyright © 2014, Texas Instruments Incorporated 11 Component Selection and Circuit Design 5.2.2 www.ti.com Selection of Input Capacitors (CIN) The dc input bulk capacitor C1 is used to provide a smooth dc voltage by filtering low frequency ac ripple voltage. For calculating the input filter capacitor, a ripple voltage of 10% (40 V) is assumed. Equation 4 determines the worst-case discharge time. 1 td = = 3.33ms 6 ´ 50 P 50 2 ´ out ´ t d 2´ (3.33m) h 0.8 = = 13.7 mF CIN ³ 2 2 (Vmin - 0.9 ´ Vmin ) (4002 - 0.9 ´ 4002 ) (4) (5) Equation 6 shows the calculation for RMS current. (See Section 5.2.11 for DMAX and Ipk details) I rms = I pk ´ Dmax = 1´ 3 0.335 = 334 mA 3 (6) Three capacitors of 47 µF / 450 V (EEUED2W470) with a 1-A ripple current rating are connected in series to get an equivalent value of approximately 15 µF. 5.2.3 Input Filter Equation 7 shows the required corner frequency of the filter. fc = fsw Att ´10 40 where • • fc is the desired corner frequency of the filter fsw is the operating frequency of the power supply (50 kHz) (7) With reasonable assumption of having 60 dB of attenuation at the switching frequency of the power supply, Equation 8 determines the cut off frequency of the filter -60 fc = 50k ´10 40 = 1.58 kHz (approximated to 1 kHz) (8) Equation 8 leads to an inductance of 2 mH, which is split in two with 1 mH being placed on both the lines of the dc bus. HT+ Figure 9. Input Section 12 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback Copyright © 2014, Texas Instruments Incorporated Component Selection and Circuit Design www.ti.com 5.2.4 Surge Protection Considering 690 V ac input with 10% variation, MOV of 750 V ac with peak-current rating of 6500 A specified for 8/20 µsec waveform has been used to suppress surge at the input. For 400-V rated drives, the voltage rating of the MOV needs to be lowered. 5.2.5 VDD Capacitor Selection (CDD) The capacitance on VDD supplies operating current to the device until the output of the converter reaches the target minimum operating voltage in constant-current regulation. The capacitance on VDD needs to supply the device operating current until the output of the converter reaches the target minimum operating voltage in constant-current regulation. Now the auxiliary winding can sustain the voltage to the UCC28711 device. The total output current available to the load and available to charge the output capacitors is the constant-current regulation target. Equation 9 assumes the output current of the flyback is available to charge the output capacitance until the minimum output voltage is achieved. There is an estimated 1 mA of gate-drive current shown in Equation 10 and 1 V of margin is added to VDD. æC ´ VOCC1 COUT1 ´ VOCC1 COUT1 ´ VOCC1 COUT1 ´ VOCC1 ö (I RUN + 1 mA) ç OUT1 + + + ÷ I OCC1 I OCC1 I OCC1 I OCC1 è ø CDD = (VDD(ON) - VDD(OFF) ) - 1 V (9) æ 760 m´ 24 100 m´16 100 m´16 100 m´16 ö (2 mA + 1 mA) ç + + + 1.875 0.14 0.14 0.083 ÷ø è CDD = = 9.95 mF » 10 mF (21 - 8) - 1 V (10) Figure 10. VDD Capacitor After CDD has been charged up to the device turn-on threshold (VVDD(on)), the UCC28700 device will initiate three small gate drive pulses (DRV) and start sensing current and voltage (see Figure 11). If a fault is detected, such as an input under voltage or any other fault, the UCC28700 device will terminate the gatedrive pulses and discharge CDD to initiate an under-voltage lockout. This capacitor will be discharged with the run current of the UCC28700 (IRUN) until the VDD turnoff threshold (VVDD(off)) is reached. The CDD discharge time (tCDDD) from the forced soft start is calculated in Equation 11 with the controller-run current (IRUN) without out-gate driver switching and the VDD turnoff threshold (VVDD(off)) of the controller. If no fault is detected, the UCC28700 device will continue driving QA and controlling the input and output currents. No soft start will be initiated. Irun = 2.1 mA VVDD(off) = 8 V dt CDD = CDD VVDD(ON) - VVDD(OFF) æ VINMAX ö - I RUN ÷ ç è RT ø TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback = 10 m 21 - 8 = 60 ms æ 1100 ö - I RUN ÷ ç è 1.88M ø 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives Copyright © 2014, Texas Instruments Incorporated (11) 13 Component Selection and Circuit Design www.ti.com VVDD(ON) = 21V VVDD 3 Initial DRV Pulses After VDD(ON) VVDD(OFF) = 8V DRV 0V Figure 11. Power-ON Sequence 5.2.6 Current Sensing For this design, a 0.75-Ω resistor is selected based on a nominal maximum current-sense signal of 0.75 V. NOTE: The actual value shown in Equation 12 needs to be tuned based on the allowable power limit during fault conditions. In this design 0.91-Ω resistor is used to limit the power less than 65 W. RCS = 0.75 = 0.75 W I PPK (12) Equation 13 determines the nominal current sense resistor power dissipation. 2 PRCS = I PRMS ´ RCS = 0.3342 ´ 0.91 = 0.1W (13) The UCC28711 device operates with cycle-by-cycle primary-peak current control. The normal operating range of the CS pin is 0.78 V to 0.195 V. There is additional protection if the CS pin reaches 1.5 V. This results in a UVLO reset and restart sequence. The current-sense (CS) pin is connected through a series resistor (RLC) to the current-sense resistor (RCS). The current-sense threshold is 0.75 V for IPP(max) and 0.25 V for IPP(min). The series resistor RLC provides the function of feed-forward line compensation to eliminate change in IPP due to change in di/dt and the propagation delay of the internal comparator and MOSFET turnoff time. There is an internal leading-edge blanking time of 235 ns to eliminate sensitivity to the MOSFET turnon current spike. The value of RCS is determined by the target output current in constant-current (CC) regulation. The value of RLC is determined by Equation 14. NOTE: The value determined in Equation 14 may require adjustments based on the noise and ringing on the current sense which is dependent on routing of the signals. 1 kΩ resistor is used in the design. R LC = K LC ´ R S1 ´ R CS ´ TD ´ N PA LP = 25 ´ 91 k ´ 0.91 ´ 300n ´ 18 = 4.44k 2.5 m where • • • • • • • 14 RLC is the line compensation resistor RS1 is the VS pin high-side resistor value RCS is the current-sense resistor value TD is the current-sense delay including MOSFET turn-off delay. Add 50 ns to the MOSFET delay. NPA is the transformer primary-to-auxiliary turns ratio LP is the transformer primary inductance. KLC is the current-scaling constant (equal to 25 A/A according to data sheet of UCC28711) 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives (14) TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback Copyright © 2014, Texas Instruments Incorporated Component Selection and Circuit Design www.ti.com RLC RCS Figure 12. Current Sense 5.2.7 Primary-Side Regulation In primary-side control, the output voltage is sensed on the auxiliary winding during the transfer of transformer energy to the secondary. To achieve an accurate representation of the secondary output voltage on the auxiliary winding, the discriminator (inside UCC28711) reliably blocks the leakage inductance reset and ringing, continuously samples the auxiliary voltage during the down slope after the ringing is diminished, and captures the error signal at the time the secondary winding reaches zero current. The internal reference on VS is 4.05 V; and VS is connected to a resistor divider from the auxiliary winding to the ground. The output-voltage feedback information is sampled at the end of the transformer secondary-current demagnetization time to provide an accurate representation of the output voltage. Timing information to achieve valley switching and to control the duty cycle of the secondary transformer current is determined by the waveform on the VS pin. It is not recommended to place a filter capacitor on this input, which would interfere with accurate sensing of this waveform. The VS pin senses the bulk-capacitor voltage to provide for ac-input run and stop thresholds. The VS pin also compensates the current-sense threshold across the ac-input range. The VS pin information is sensed during the MOSFET on-time. For the ac-input run or stop function, the run threshold on VS is 225 μA and the stop threshold is 80 μA. A wide separation of run and stop thresholds allows clean startup and shut-down of the power supply with the line voltage. The VS pin also senses the bulk capacitor voltage to provide for ac-input run and stop thresholds, and to compensate the current-sense threshold across the ac-input range. This information is sensed during the MOSFET on-time. For the ac-input run/stop function, the run threshold on VS is 225 μA and the stop threshold is 80 μA. A wide separation of run and stop thresholds allows clean start up and shut down of the power supply with the line voltage. The values for the auxiliary voltage divider upper-resistor RS1 and lower-resistor RS2 can be determined by Equation 15 and Equation 16. VIN(RUN) 375 RS1 = = = » 92k N PA ´ I VSL(RUN) 18 ´ 225 m (Rounded off to 91 k) where • • • NPA is the transformer primary-to-auxiliary turns ratio VIN(run) is the converter input start-up (run) voltage IVSL(run) is the run threshold for the current pulled out of the VS pin during the MOSFET on-time (equal to 220 µA max from UCC28711 data sheet) TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives Copyright © 2014, Texas Instruments Incorporated (15) 15 Component Selection and Circuit Design RS2 = www.ti.com RS1 ´ VVSR 91 k ´ 4.05 = = 30.2 k NAS ´ (VOCV + VF ) - VVSR (0.66 ´ 24.6) - 4.05 (Rounded off to 30 k) where • • • • • VOCV is the regulated output voltage of the converter VF is the secondary rectifier forward voltage drop at near-zero current NAS is the transformer auxiliary-to-secondary turns ratio RS1 is the VS divider high-side resistance VVSR is the CV regulating level at the VS input (equal to 4.05-V typical from UCC28711 data sheet) (16) RS1 RS2 Figure 13. Primary Feedback The output over-voltage function is determined by the voltage feedback on the VS pin. If the voltage sample on VS exceeds 115% of the nominal VOUT, the device stops switching and also stops the internal current consumption of IFAULT, which discharges the VDD capacitor to the UVLO turnoff threshold. After that, the device returns to the start state and a start-up sequence ensues. Protection is included in the event of component failures on the VS pin. If complete loss of feedback information on the VS pin occurs, the controller stops switching and restarts. 16 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback Copyright © 2014, Texas Instruments Incorporated Component Selection and Circuit Design www.ti.com 5.2.8 MOSFET Gate-Drive The DRV pin of UCC28711 device is connected to the MOSFET gate pin through a series resistor. The gate driver provides a gate-drive signal limited to 14 V. The turnon characteristic of the driver is a 25-mA current source, which limits the turnon dv/dt of the MOSFET drain. This reduces the leading-edge current spike, but still provides gate-drive current to overcome the Miller plateau. The gate-drive turnoff current is determined by the low-side driver RDS(on) and any external gate-drive resistance. In order to improve the efficiency and to reduce switching loss in the power device, an external BJT-based current buffer with a higher voltage rating (high Qg) may be used to drive the MOSFETs. PGND Figure 14. MOSFET Gate Drive 5.2.9 Overvoltage Detection The LMS33460 device is a micropower, under-voltage sensing circuit with an open-drain output configuration, which requires a pull resistor. The LMS33460 features a voltage reference and a comparator with precise thresholds, and built-in hysteresis to prevent erratic-reset operation. This IC generates an active output whenever the input voltage drops below 3.0 V. The resistor divider shown in Figure 15 is derived with 1200 V dc as the over-voltage trip point. Zener diode D32 is used to clamp the input voltage at LMS33460 to less than 8 V (absolute max of the device) when the dc bus voltage is at its max of 1200 V dc. The device has a minimum hysteresis voltage of 100 mV, which translates to approximately 11 V on the dc bus. Hysteresis can also be adjusted with R29. NTC Figure 15. Undervoltage Protection TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives Copyright © 2014, Texas Instruments Incorporated 17 Component Selection and Circuit Design www.ti.com The UCC28711 device has an NTC input, which can be used to interface an external negativetemperature-coefficient resistor for remote temperature sensing to allow user-programmable external thermal shutdown. The shutdown threshold is 0.95 V with an internal 105-μA current source, which results in a 9.05-kΩ thermistor shutdown threshold. Pulling the NTC pin to low shuts down the PWM action. The signal from LMS33460 is interfaced to the NTC pin to shut down the controller during over voltage. 5.2.10 HV Startup The UCC28710 device has an internal 700-V start-up switch. Because the dc bus can be as high as 1200 V dc, an external Zener voltage regulator is used to limit the voltage at the HV pin to about 550 V dc. The typical startup current is approximately 300 μA, which provides fast charging of the VDD capacitor. The internal HV start-up device is active until VDD exceeds the turnon UVLO threshold of 21 V at which time the HV start-up device is turned off. In the off state, the leakage current is very low to minimize standby losses of the controller. When VDD falls below the 8.1-V UVLO turn-off threshold, the HV start-up device is turned on. HT+ VDD HT+ R47 470k C10 10 µF R43 470k C32 1µF R40 470k PGND R37 470k U1 VDD HV 8 HV_START 1 1 3 4 D13 P4KE550 VS NTC DRV GND CS 6 2 2 5 PGND UCC28711D Figure 16. Start-Up Circuit For drives with two capacitors connected in series in the dc link, the midpoint of the series can be connected to the HV pin of the UCC28711 device. The midpoint voltage will vary from 200 V to 600 V (for an input of 400 V dc to 1200 V dc), which would be within the limit of 700-V start-up switch of UCC28711. 5.2.11 Transformer Calculations Equation 17 shows the calculation for the transformer turns ratio primary to secondary (a1) based on voltsecond balance. NP L PM DMAX ´ (Vin MIN - VAON - VRCS ) a1 = = = = » 12 NS L SM DMAG ´ (VOUT + VDG ) where • • • • LSM is the secondary magnetizing inductance VAON = 5 V, estimated voltage drop across FET during conduction VRCS = 0.75 V, voltage drop across current sense resistor VDG = 0.6 V, estimated forward voltage drop across output diode Equation 18 shows the calculation for maximum duty cycle (DMAX). 12 ´ DMAG ´ (VOUT + VDG ) 12 ´ 0.425 ´ 24.6 = = 0.335 DMAX = Vin MIN - VAON - VRCS 375 - 5 - 0.75 (17) (18) Equation 19 shows the calculation for the transformer primary-peak current (IPPK) based on a minimum flyback input voltage. 2 ´ POUT 2 ´ 50 W I PPK = = =1A h ´ Vin MIN ´ DMAX 0.8 ´ 375 ´ 0.335 (19) 18 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback Copyright © 2014, Texas Instruments Incorporated Component Selection and Circuit Design www.ti.com Equation 20 shows the calculation for the selected primary magnetizing inductance (LPM) based on minimum flyback input voltage, transformer, primary peak current, efficiency, and maximum switching frequency (fMAX). 2 ´ POUT 2 ´ 50 W h 0.8 L PM = 2 = = 2.5 mH I PPK ´ FMAX 1 2 ´ 50 kHz (20) Equation 21 shows the calculation for the transformer auxiliary to secondary turn ratio (a2). VDDMIN + VDE 16 + 0.3 N = = 0.66 a2 = A = NS VOUT + VDG 24.6 where • • VDDMIN = 16 V VDE = 0.3 V, estimated auxiliary diode forward voltage drop (21) Equation 22 shows the calculation for the transformer primary RMS current (IPRMS). I PRMS = I PPK DMAX = 1´ 3 0.335 = 0.334 A 3 (22) Equation 23 through Equation 26 show the calculations for the transformer secondary peak current RMS current (ISPK). POUT ´ 2 90 IS1PK (24 V Output) = = = 8.6 A VOUT ´ DMAG 24.6 ´ 0.425 (3.23 Arms) IS2PK ( ±16 V Output) = (23) POUT ´ 2 9 = = 0.638 A VOUT ´ DMAG 33.2 ´ 0.425 (0.24 Arms) (24) POUT ´ 2 1 IS3PK ( ±6 V Output) = = = 0.357 A VOUT ´ DMAG 6.6 ´ 0.425 (0.134 Arms) (25) POUT ´ 2 30 IAUX _ PK (16 V Output) = = = 4.25 A VOUT ´ DMAG 16.6 ´ 0.425 (1.6 Arms) 5.2.12 (26) Output Diodes 5.2.12.1 +24 V Output Diode (DG1) Equation 27 shows the calculation for the diode reverse voltage (VRDG). V 1200 VRDG1 = VOUT1 + INMAX = 24 + = 124 V a1 12 (27) Equation 28 shows the calculation for the peak output diode (IDGPK). IDG1PK = IS1PK = 8.6 A (28) For this design, Schottky diode of 20 A, 200-V rating with a forward voltage drop (VFDG) of 0.88 V is used. VFDG = 0.88 V Equation 29 calculates the estimated diode power loss (PDG). P ´V 45 ´ 0.88 PDG1 = OUT1 FDG = = 1.65 W VOUT 24 TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives Copyright © 2014, Texas Instruments Incorporated (29) 19 Component Selection and Circuit Design 5.2.12.2 www.ti.com +16 V Auxiliary Output Diode (DG2) Equation 30 shows the calculation for the diode reverse voltage (VRDG). V 1200 VRDG2 = VAUX _ OUT + INMAX = 16 + = 116 V a1 12 (30) Equation 31 shows the calculation for the peak output diode (IDG2PK). IDG2PK = IAUX_PK = 4.25 A (1.6 Arms) (31) For this design a 3 A, 200-V super-fast rectifier (MURS320-13-F) with a forward voltage drop (VFDG) of 875 mV at 3 A was selected. Equation 32 determines the estimated diode power loss (PDG2). PAUX _ OUT ´ VFDG2 15 ´ 0.875 PDG2 = = = 0.82 W VAUX _ OUT 16 (32) The same diode has been used for ±16 V output and isolated +6 V output. 5.2.13 Output Capacitors Equation 33 shows the calculation for selecting the output ESR based on 90% of the allowable output ripple voltage. Vripple ´ 0.9 250m ´ 0.9 ESRCOUT _ 24V = = = » 26mW I SPK 8.6 A (33) Equation 34 through Equation 37 show the calculations for selecting the output capacitors, which was selected based on the required ripple voltage requirements. P 45 20 m´ OUT 20 m´ VOUT ´ 2 24 ´ 2 = = » 750 mF COUT _ 24V ³ Vripple 0.025 (34) 4.5 20 m´ 16 ´ 2 COUT _16V ³ = » 120 mF 0.025 (35) 0.5 20 m´ 6´ 2 COUT _ 6V ³ = » 120 mF 0.01 (36) 15 20 m´ 16 ´ 2 COUT _ AUX ³ = » 120 mF 0.1 (37) Equation 38 shows the calculation for estimating the total output capacitor RMS current (ICOUT_RMS). ICOUT _ RMS æI ´ DMAG = ç SPK ç 3 è 2 2 ö æP ö ÷ - ç OUT ÷ ÷ è 3 ø ø (38) 2 I COUT _ RMS _ 24V = 2 æ 8.6 ´ 0.425 ö æ 45 ö çç ÷÷ ç 24 ÷ = 2.6 A 3 è ø è ø (39) Two 330 µF, 35-V aluminum-electrolytic capacitors with ripple-current ratings of 1.43 A are connected in parallel at the output diode to support the ripple current. 2 ICOUT _ RMS _16V = 2 æ 0.638 ´ 0.425 ö æ 4.5 ö = 640mA çç ÷÷ - ç ÷ 3 è 16 ø è ø (40) A 120 µF, 50-V capacitor with a ripple-current rating of 1.6 A is connected at both +16 V and –16 V outputs. 20 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback Copyright © 2014, Texas Instruments Incorporated Component Selection and Circuit Design www.ti.com 2 ICOUT _ RMS _ 6V = 2 æ 0.357 ´ 0.425 ö æ 0.5 ö çç ÷÷ - ç ÷ = 0.1A 3 è 6 ø è ø (41) 2 ICOUT _ RMS _ AUX = 2 æ 4.25 ´ 0.425 ö æ 15 ö çç ÷÷ ç 16 ÷ = 1.3A 3 è ø è ø (42) A 120 µF, 50-V capacitor with a ripple-current rating of 1.6 A is used in this design. 5.2.14 MOSFET Selection To meet the voltage and current requirements, 950 V, 2-A rated MOSFET (STF2N95K5) with the following characteristics is chosen. RDSON = 4.2 Ω COSS = 9 pF IDRIVE = 0.025 A, maximum FET gate drive turn ON current (limited by UCC28711) Maximum gate-sink current is internally limited and is approximately 0.2 A Qg = 10 nC, gate charge just above the Miller plateau Equation 43 determines the estimated VDS fall time. Qg 10nC tf = = = 50ns Idrive 0.2 A 5.2.14.1 FET Average Switching Loss (PSW) PSW = 5.2.14.2 (43) 1 1 VPK ´ I PK ´ TF ´ FSW = ´ 800 ´ 1 ´ 50n ´ 50kHz = 1W 2 2 (44) Power Loss by Driving the FET Gate (Pg): Pg = 14 V × Qg × fmax = 14 V × 10 nC × 50 kHz = 7 mW (45) Qg1, gate charge at 10-V drive clamp Vg = 14 V 5.2.14.3 FET COSS Power Dissipation (PCOSS) Equation 46 and Equation 47 determine the average FET drain to source capacitance. 2 ´ COSS ´ PCOSS VDS _ TEST VDS = 2 ´ 9pF ´ 100 = 6.4pF 800 C 6.4p 2 = OSS ´ VPK ´ FMAX = ´ 8002 ´ 50kHz = 0.1W 2 2 TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives Copyright © 2014, Texas Instruments Incorporated (46) (47) 21 Component Selection and Circuit Design 5.2.14.4 www.ti.com Power Loss from Rdson (PRDSON) 2 PRDSON = I PRMS ´ RDSON = 0.3342 ´ 4.2 = 0.47 W (48) (49) (50) (51) (52) Total power loss per MOSFET = 1 + 0.1 + 0.47 = 1.57 W Thermal resistance of MOSFET, Junction to Case, Max = 2.78°C/W Thermal resistance of heat sink, Max = 15°C/W MOSFET temperature rise = 17.78 × 1.57 = 28°C/W With ambient temperature varying from –20°C/W to 65°C/W, the FET temperature should be in the range of 8°C to 93°C (less than 150°C as specified in MOSFET STF2N95K5 data sheet). MOSFET with a voltage rating of ≥ 1000 V can be used if higher de-rating is required to enhance reliability. 5.2.15 Input-Voltage Sensing ac 1. 2. 3. input voltage and dc link voltage are measured in the drives for various reasons. Detection of single phase failure dc link undervoltage and overvoltage condition For controlling the inverter output voltage When the drive application does not mandate high-accuracy measurements, the flyback converter can be used to measure the ac input as well as the dc link voltage. When the primary switch is ON, the induced voltage at the secondary (see D24 in Figure 17) will be the dc link voltage times the turn ratio, which will also be proportional to the ac mains input voltage. This voltage is rectified and filtered with RC network. Voltage scaling can be performed based on the ADC input-voltage range. At 1200 V dc input with a turns ratio of 18, the forward-induced voltage is determined by Equation 53 and Equation 54. 1200 Vdc MEAS (MAX) = = 66.67 V 18 (53) 400 Vdc MEAS (MIN) = = 22.22 V 18 (54) 1k The voltage determined in Equation 53 and Equation 54 is stepped down through a resistive divider 11 k to scale it to 6.06 V and 2.02 V. This step-down ratio can be adjusted based on the application requirements. HT+ T1 14 2 +24VDC 1 1 Primary 2 13 +16VDC 1 4 12 11 VFB VDC_MEAS 6 Auxiliary GND GND 9 1 7 ETD 29 PGND GND 2 -16VDC 8 D24 VDC_MEAS 1N4937-E3 600V R10 100 C26 2.2µF C24 2.2µF R8 10k J5 1 2 2 R5 1.00k C20 0.1µF 1729018 GND 3 1 PGND Figure 17. DC Link Voltage Measurement 22 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback Copyright © 2014, Texas Instruments Incorporated Component Selection and Circuit Design www.ti.com 5.2.16 Transformer Construction Table 1. Magnetic Details Core Type Core Material Bobbin ETD29 CF138/N87 14 Pin (Vertical) Table 2. Winding Details (1) (1) Winding No. of Turns Start Pin End Pin Inductance W1 142 4 1 2.5 mH ± 10% W2 8 6 7 – W3 Tapped 4 14 13 – 8 13 12 – W4 8 12 11 – W5 3 9 4 – Use of Litz wire would help in reducing losses in the transformer. Electrical Requirements: • Leakage inductance between pins 1 and 4 with all other pins shorted to 100 μH max • Use triple insulated wire for W3, W4, W5 Winding Procedure: • Wind 48 turns of primary (W1) in one layer, starting at pin 4 and finishing at pin 3 • Basic insulation • Wind bias (W2) uniformly spread in one layer, starting at pin 6 and ending at pin 7 • Reinforced Insulation • Wind W3 in one layer; start at pin 14 and wind 4 turns ending at pin 13; continue at pin 13 and wind 8 more turns to end at pin 12 • Basic insulation • Wind W4 uniformly spread in one layer, starting at pin 12 and ending at pin 11 • Reinforced insulation • Wind remaining 94 turns of primary (W1) in two layers, starting at pin 3 and finishing at pin 1 • Reinforced insulation • Wind W5 uniformly spread in one layer, starting at pin 9 and ending at pin 8 • Reinforced insulation • Gap core suitably to get required primary inductance • Bond the core to avoid audible noise • Vacuum impregnate with varnish • Cut off pin 3 without damaging the termination on it TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives Copyright © 2014, Texas Instruments Incorporated 23 Component Selection and Circuit Design www.ti.com Figure 18. Transformer Pinout 24 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback Copyright © 2014, Texas Instruments Incorporated Test Data www.ti.com 6 Test Data 6.1 Functional Test Results Figure 19. Lower FET Voltage at 400-V Input, 50-W Output (CH4: Vgs and CH2: Vds) Figure 20. Upper FET Voltage at 400-V Input, 50-W Output (CH3: Vgs and CH1: Vds) Figure 21. Lower FET Voltage at 1200-V Input, 50-W Output (CH4: Vgs and CH2: Vds) Figure 22. Upper FET Voltage at 1200-V Input, 50-W Output (CH3: Vgs and CH1: Vds) Figure 23. 24-V Output Diode Voltage Stress with VIN = 1200 V DC and 50-W Output TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives Copyright © 2014, Texas Instruments Incorporated 25 Test Data 6.2 www.ti.com Output Ripple Under Different Test Conditions Figure 24. Ripple at 24-V Output with VIN = 400 V DC and Full Load Figure 25. Ripple at 24-V Output with VIN = 1200 V DC and Full Load Figure 26. Ripple at ±16-V Output with VIN = 400 V DC and Full Load (CH2: +16 V, CH1: –16 V) Figure 27. Ripple at ±16–V Output with VIN = 1200 V DC and Full Load (CH2: +16 V, CH1: –16 V) Figure 28. Ripple at +6-V Output with VIN = 400 V DC and Full Load Figure 29. Ripple at +6-V Output with VIN = 1200 V DC and Full Load 26 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback Copyright © 2014, Texas Instruments Incorporated Test Data www.ti.com 6.3 Efficiency 90 88.5 Efficiency at Nominal Input Voltage - 690VAC/976VDC Efficiency vs Input Voltage at Full Load (50W) 88 80 87.5 70 87 86.5 Efficiency (%) Efficiency (%) 60 50 40 86 85.5 85 84.5 30 84 20 Output Load +24V @ 45W r6V @ 4.5W +6V @ 0.5W 10 83.5 83 82.5 400 0 0 5 10 15 20 25 30 Output Power (W) 35 40 45 50 55 700 800 Input Voltage (VDC) 900 1000 1100 1200 Line Regulation 24.21 24V Output Line Regulation 24.2 24.19 Output Voltage (+6V) 24.18 Output Voltage (+24V) 600 Figure 31. Efficiency vs Input Voltage at Po = 50 W Figure 30. Efficiency vs Output Load at VIN = 976 V DC 6.4 500 24.17 24.16 24.15 24.14 24.13 24.12 24.11 24.1 24.09 400 500 600 700 800 Input Voltage (VDC) 900 1000 1100 1200 Figure 32. 24-V Output Line Regulation with 45-W Load 6 5.995 5.99 5.985 5.98 5.975 5.97 5.965 5.96 5.955 5.95 5.945 5.94 5.935 5.93 5.925 5.92 400 6V Output Line Regulation 500 600 700 800 Input Voltage (VDC) 900 1000 1100 1200 Figure 33. 6-V Output Line Regulation with 0.5-W Load 16.65 r16V Output Line Regulation Output Voltage (+16V) Output Voltage (-16V) 16.6 Absolute Voltage (V) 16.55 16.5 16.45 16.4 16.35 16.3 16.25 400 500 600 700 800 Input Voltage (VDC) 900 1000 1100 1200 Figure 34. ±16-V Output Line Regulation with 4.5-W Load TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives Copyright © 2014, Texas Instruments Incorporated 27 Test Data 6.5 www.ti.com Load Regulation 6.5 25 24V Output Load Regulation 6V Output Load Regulation 6.4 6.3 Output Voltage (+6V) Output Voltage (+24V) 24.8 24.6 24.4 6.2 6.1 6 5.9 5.8 24.2 5.7 24 0 200 400 600 800 1000 1200 Output Current (mA) 1400 1600 1800 5.6 2000 0 Figure 35. +24-V Output Load Regulation with VIN = 976 V DC 10 20 30 40 50 Output Current (mA) 60 70 80 90 Figure 36. +6-V Output Load Regulation with VIN = 976 V DC 17 r16V Output Load Regulation Output Voltage (+16V) Output Voltage (-16V) Absolute Voltage (V) 16.8 16.6 16.4 16.2 16 0 20 40 60 80 Output Current (mA) 100 120 140 Figure 37. ±16-V Output Load Regulation with VIN = 976 V DC 6.6 Overload Test and Output Power Limit 65 65 Output Power Limit 60 55 55 Output Power (W) Output Power (W) Output Current Limit 60 50 45 40 35 45 40 35 30 30 25 1850 25 1900 1950 2000 2050 2100 2150 2200 2250 24V Output Current (mA) 2300 2350 2400 2450 2500 Figure 38. Overload and Current Limit at +24-V Output with VIN = 976 V DC 28 50 8 10 12 14 16 18 Output Voltage (+24V) 20 22 24 26 Figure 39. Overload at +24-V Output Voltage vs Output Power with VIN = 976 V DC 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback Copyright © 2014, Texas Instruments Incorporated Test Data www.ti.com 6.7 dc Link Voltage Measurement 4.5 5.4 5.1 4 4.5 DC Link Sense (V) 3.5 DC Link Sense (V) DC Link Sense Voltage vs Input Voltage at Full Load 4.8 3 2.5 2 4.2 3.9 3.6 3.3 3 2.7 2.4 1.5 2.1 DC Link Sense Voltage vs Load at Nominal Input Voltage (690VAC/976VDC) 1 0 5 10 15 20 25 30 Output Power (W) 35 40 45 Figure 40. DC Link Voltage Measurement with Varying Output Load 6.8 50 1.8 400 500 600 700 800 Input Voltage (VDC) 900 1000 1100 1200 Figure 41. DC Link Voltage Measurement with Full Load Undervoltage and Overvoltage Test Figure 42 and Figure 43 capture the input overvoltage and under voltage limits. When the input voltage exceeds 1220 V dc, the PWM controller is shut down and it recovers when the input voltage falls back to approximately 950 V dc. The hysteresis in turnoff and turnon voltage can be adjusted by varying R29. Figure 42. DC Link Voltage Measurement with Full Load The power supply turns ON at approximately 375 V dc and shuts down when the input voltage reduces below 150 V dc. The ratio of turn ON to turn OFF is fixed for under-voltage shutdown operation and is controlled within the UCC28711 device . Figure 43. DC Link Voltage Measurement with Full Load TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives Copyright © 2014, Texas Instruments Incorporated 29 Layout Guidelines for UCC28711 7 www.ti.com Layout Guidelines for UCC28711 Good layout is critical for proper functioning of the power supply. Major guidelines on the layout for the proper functioning of the controller is described in Figure 44, Figure 45, and Figure 46. Figure 44. Layout Diagram One Figure 45. Layout Diagram Two Figure 46. Layout Diagram Three 30 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback Copyright © 2014, Texas Instruments Incorporated Design Files www.ti.com 8 Design Files 8.1 Schematics 400 - 1200Vdc 2 HT+ 1N4007 1000V 1N4007 1000V R4 220K 768772102 D2 1N4007 1000V 3Phase AC Input (400-690Vac) D6 1N4007 1000V 220 D22 1.5KE200A C6 47µF 450 R49 470k R36 470k +24VDC 7447462022 C14 330UF 35V C17 330UF 35V R11 10k C19 120UF 50V D21 UF4007 1000V C25 1uF 35V 24V / 45W GND T1 GND 1 14 J6 -16VDC 1 C5 B32672L1333J C7 47µF 450 R2 EMC-xxRKI 1714984 R51 470k R32 470k Q1 STF2N95K5 D4 1N4007 1000V C4 1 D7 1N4007 1000V C8 47µF 450 D11 1N4007 1000V R52 470k C40 47pF 2 2 2 D3 1N4007 1000V 2 CD12-E2GAxxxMYGS D8 1N4007 1000V R25 10 L2 11 VDC_MEAS GND 9 Auxiliary D27 1 7 C18 120UF 50V C29 0.1µF 35V C16 120UF 50V 6 2 R14 10k +24VDC 5 6 4.5W C31 0.1µF 35V 1729160 GND +24VDC R16 10k -16VDC 2 MURS320-13-F GND R15 10k C30 0.1µF 35V C15 120UF 50V J4 VFB 1 C10 10 µF 2 C11 120UF 50V C32 1µF R28 36.5k GND* GND C38 100pF R26 30K LMS33460MG/NOPB ISENSE 1SS355TE-17 2 1 LD5 Green A LD2 Green GND GND GND LD1 Green C LD4 Green C LD3 Green 1 2 A 1 D30 1 GND_ISO 1.0k PGND ISENSE VAUX C35 680pF PGND R17 6.80k 3 R23 VAUX R6 6.80k 2 0 Q4 MMBT3906 UCC28711D 2 NC Q5 2N7002P,215 1 0 R20 0 A R30 C 10.0 -16VDC R9 11k 1 5 A 6 C CS Q2 STF2N95K5 R19 R7 6.80k 1 DRV GND 3 NTC R21 R12 2.00k +24VDC 2 Q3 MMBT3904 1 VS 1 PGND PGND PGND 2 HV_START A 8 C HV +16VDC 2 3 VDD U2 2 3 1729018 2 2 4 4 C20 0.1µF GND +6V_ISO HS2 513201B02500G 2 2 D32 7.5V U1 3 VOUT J5 1 2 R5 1.00k C36 1µF PGND 1 R29 VIN R8 10k C24 2.2µF VDD 1 R27 91k 511k 1 C26 2.2µF PGND C37 1000pF PGND 5 100 VFB MURS320-13-F 1SS355TE-17 D18 1N4937-E3 R24 205 600V 1N4937-E3 600V D28 D29 2 R10 GND VAUX PGND R31 44.2k 1729018 2 D24 D13 P4KE550 R33 2.00Meg 1 VDC_MEAS (+16V) HV_START R35 2.00Meg 1 2 C13 2 1 R37 470k C12 2 R38 2.00Meg GND GND_ISO 1 R40 470k PGND HT+ 1 VDD R41 2.00Meg GND 3 R43 470k PGND HT+ C23 0.1µF +6V_ISO 0.5W GND_ISO PGND HT+ R44 2.00Meg C22 0.1µF C27 0.1µF PGND R47 470k -16VDC +6V_ISO 1 768772102 R46 2.00Meg +16VDC C21 0.1µF MURS320-13-F D26 750342585 HS1 513201B02500G D15 P6KE400A 342V C41 47pF +16VDC 3 4 PGND DC- 1 2 +16VDC 1 MURS320-13-F 8 C42 1000pF R53 470k D12 1N4007 1000V 2 4 1 850 ohm D31 12V 1SMB5927BT3G D16 P6KE400A 342V 1 1 1 C1 13 C34 47pF VFB L4 R3 C2 D25 Primary 12 RV3 1080V C3 D19 UF4007 1000V 3 J1 RV1 1080V R34 470k 2 RV2 1080V R50 470k 2 EMC-xxRKI PE L3 MBR20200CT-LJ R18 10 PGND EMC-xxRKI HS3 265-118ABH-22 2 3 R39 470k R1 1 2 3 D23 1 C9 B32672L1333J D10 1N4007 1000V 330pF 1 D9 1N4007 1000V HT+ 1 PGND D5 1N4007 1000V 2 D1 1N4007 1000V R42 470k R48 470k 1714968 C28 R13 C33 4700pF 2 D17 DC+ 1 2 3 1 D14 1 R45 470k L1 J2 2 DC Input D20 1.5KE200A PGND J3 R22 0.91 PGND PGND 1 2 VAUX C39 0.1µF 15W (Optional Output) 1729018 PGND Figure 47. Schematic for 400- to 690-V ac Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives Copyright © 2014, Texas Instruments Incorporated 31 Design Files 8.2 www.ti.com Bill of Materials To download the bill of materials (BOM), see the design files at TIDA-00173. Table 3. BOM Quantity Reference Part Description Manufacturer Manufacturer Part Number PCB Footprint Note 6 C1, C2, C3, C4, C12, C13 CAP, X1Y1, 250VAC TDK Corporation CD12-E2GAxxxMYGS YCAP_MODIFIED Fitted 2 C5, C9 CAP FILM 0.033UF 1.6KVDC RADIAL EPCOS Inc B32672L1333J CAP_18X9_17.5 Fitted 3 C6, C7, C8 CAP, AL, 47uF, 450V, +/-20%, 0.609529 ohm, TH Panasonic EEUED2W470 CAPPR7.5-18X31.5 Fitted 1 C10 CAP, AL, 10uF, 35V, +/-20%, TH Nichicon UVR1V100MDD1TA CAPPR2-5x11 Fitted 5 C11, C15, C16, C18, C19 CAP 120UF 50V RADIAL United Chemi-Con EKZN500ELL121MH15D HE_800x1150 Fitted 2 C14, C17 CAP ALUM 330UF 35V 20% RADIAL Rubycon 35ZL330MEFC10X16 R7_1000x1250 Fitted 6 C20, C21, C22, C23, C27, C39 CAP, CERM, 0.1uF, 50V, +/-10%, X7R, 0805 Kemet C0805C104K5RACTU 0805_HV Fitted 2 C24, C26 CAP, CERM, 2.2uF, 100V, +/-10%, X7R, 1210 MuRata GRM32ER72A225KA35L 1210 Fitted 1 C25 CAP, CERM, 1uF, 35V, +/-10%, X7R, 0603 Taiyo Yuden GMK107AB7105KAHT 0603 Fitted 1 C28 CAP, CERM, 330pF, 630V, +/-5%, C0G/NP0, 1206 TDK C3216C0G2J331J 1206 Fitted 3 C29, C30, C31 CAP, CERM, 0.1uF, 35V, +/-10%, X7R, 0603 Taiyo Yuden GMK107B7104KAHT 0603 Fitted 1 C32 CAP, CERM, 1uF, 35V, +/-10%, X7R, 0805 Taiyo Yuden GMK212B7105KG-T 0805_HV Fitted 1 C33 CAP, CERM, 4700pF, 1000V, +/-10%, X7R, 1206 MuRata GRM31BR73A472KW01L 1206 Fitted 1 C34 CAP, CERM, 47pF, 1000V, +/-5%, C0G/NP0, 1206 Vishay-Vitramon VJ1206A470JXGAT5Z 1206 Fitted 1 C35 CAP, CERM, 680pF, 100V, +/-10%, X7R, 0603 AVX 06031C681KAT2A 0603 Fitted 0 C36 CAP, CERM, 1uF, 35V, +/-10%, X7R, 0805 Taiyo Yuden GMK212B7105KG-T 0805_HV Not Fitted C37 CAP, CERM, 1000pF, 100V, +/-10%, X7R, 0805 Kemet C0805C102K1RACTU 0805_HV Fitted 1 C38 CAP, CERM, 100pF, 50V, +/-5%, C0G/NP0, 0603 TDK C1608C0G1H101J 0603 Fitted 0 C40, C41 CAP, CERM, 47pF, 1000V, +/-5%, C0G/NP0, 1206 Vishay-Vitramon VJ1206A470JXGAT5Z 1206 Not Fitted 1 C42 CAP, CERM, 1000pF, 50V, +/-5%, X7R, 0805 Kemet C0805C102J5RACTU 0805_HV Fitted 14 D1, D2, D3, D4, D5, D6, D7, D8, D9, D10, D11, D12, D14, D17 Diode, P-N, 1000V, 1A, TH Fairchild Semiconductor 1N4007 DO-41 Fitted 1 D13 TVS DIODE 495VWM 798VC AXIAL Littelfuse Inc P4KE550 DO-41 Fitted TVS DIODE 342VWM 548VC DO15 Fairchild Semiconductor P6KE400A DO-204AC_VERT Fitted 1N4937-E3 DO-41 Fitted UF4007 DO-204AC_VERT Fitted Fitted 1 2 32 D15, D16 2 D18, D24 Diode, Switching, 600V, 1A, TH VishaySemiconductor 2 D19, D21 DIODE FAST REC 1KV 1A DO41 Fairchild Semiconductor 2 D20, D22 TVS DIODE 171VWM 274VC AXIAL Littelfuse Inc 1.5KE200A Zener_1.5KE200A_VE RT 1 D23 DIODE SCHOTTKY 200V 10A TO220AB Diodes Incorporated MBR20200CT-LJ TO-220AB Fitted 4 D25, D26, D27, D28 DIODE SUPERFAST 200V 3A SMC Diodes Incorporated MURS320-13-F SMC Fitted 1 D29 DIODE SMALL SIGNAL 80V 0.1A 2UMD Rohm 1SS355TE-17 SOD-323 Fitted 0 D30 DIODE SMALL SIGNAL 80V 0.1A 2UMD Rohm 1SS355TE-17 SOD-323 Not Fitted 1 D31 DIODE ZENER 12V 3W SMB ON Semiconductor 1SMB5927BT3G SMB Fitted 1 D32 Diode, Zener, 7.5V, 200mW, SOD-323 Diodes Inc. MMSZ5236BS-7-F sod-323 Fitted 6 FID1, FID2, FID3, FID4, FID5, FID6 Fiducial mark. There is nothing to buy or mount. N/A N/A Fiducial10-20 Fitted 4 H1, H2, H3, H4 Machine Screw, Round, #4-40 x 1/4, Nylon, Philips panhead B&F Fastener Supply NY PMS 440 0025 PH NY PMS 440 0025 PH Fitted 4 H5, H6, H7, H8 Standoff, Hex, 0.5"L #4-40 Nylon Keystone 1902C Keystone_1902C Fitted 2 HS1, HS2 HEATSINK TO-218/TO-247 W/PINS 2" Aavid 513201B02500G HSINK_513201B02500 Fitted 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design TIDU412A – September 2014 – Revised November 2014 for Motor Drives Submit Documentation Feedback Copyright © 2014, Texas Instruments Incorporated Design Files www.ti.com Table 3. BOM (continued) Quantity Reference Part Description Manufacturer Manufacturer Part Number PCB Footprint Note 1 HS3 Heat Sinks TO-220 VERTICAL MNT Wakefield Thermal Solutions 265-118ABH-22 HEATSINK_265118ABH-22 Fitted 1 J1 Terminal Block, 3x1, 9.52MM, TH Phoenix Contact 1714984 Phoenix_1714984 Fitted 1 J2 Terminal Block, 3x1, 6.35 mm, TH Phoenix Contact 1714968 Phoenix_1714968 Fitted 3 J3, J4, J5 TERM BLOCK 2POS 5mm, TH Phoenix Contact 1729018 Phoenix_1729018 Fitted 1 J6 Terminal Block, 6x1, 5.08mm, Th Phoenix Contact 1729160 Phoenix_1729160 Fitted L1, L2 Inductor, Shielded Drum Core, Metal Composite, 1mH, 0.5A, 1.7 ohm, TH Wurth Elektronik 768772102 IND_WE-TI_8095 Fitted 1 L3 Inductor, Unshielded Drum Core, Ferrite, 2.2 uH, 4.3A, 0.01 ohm, TH Wurth Elektronik 7447462022 IND_WE-TI_XS Fitted 1 L4 Ferrite Bead, 800 ohm @ 100MHz, 8A, 1206 Wurth Electronics Inc 74279244 1806 Fitted 1 LBL1 Thermal Transfer Printable Labels, 0.650" W x 0.200" H - 10,000 per roll Brady THT-14-423-10 Label_650x200 Fitted 5 LD1, LD2, LD3, LD4, LD5 LED SmartLED Green 570NM OSRAM LG L29K-G2J1-24-Z LED0603AA Fitted 2 Q1, Q2 MOSFET N-CH 950V 2A TO220FP STMicroelectronic s STF2N95K5 TO-220AB Fitted 0 Q3 Transistor, NPN, 40V, 0.2A, SOT-23 Fairchild Semiconductor MMBT3904 SOT-23 Not Fitted 0 Q4 Transistor, PNP, 40V, 0.2A, SOT-23 Fairchild Semiconductor MMBT3906 SOT-23 Not Fitted 2N7002P,215 SOT-23 Fitted 2 1 Q5 MOSFET, N-CH, 60V, 0.36A, SOT-23 NXP Semiconductor 3 R1, R2, R3 Resistor, Fusible, 2W, 5% Welwyn EMC-xxRKI R_AXIAL_VERT_DIA43 Fitted RES 220K OHM 3W 1% AXIAL TT Electronics/IRC GS-3-100-2203-F-LF RES_570 x 1310 Fitted 1 R4 1 R5 RES, 1.00k ohm, 1%, 0.125W, 0805 Vishay-Dale CRCW08051K00FKEA 0805_HV Fitted 3 R6, R7, R17 RES, 6.80k ohm, 0.1%, 0.125W, 0805 Susumu Co Ltd RG2012P-682-B-T5 0805_HV Fitted 1 R8 RES, 10k ohm, 5%, 0.125W, 0805 Panasonic ERJ-6GEYJ103V 0805_HV Fitted 1 R9 RES, 11k ohm, 5%, 0.125W, 0805 Vishay-Dale CRCW080511K0JNEA 0805_HV Fitted RES, 100 ohm, 0.1%, 0.125W, 0805 Stackpole Electronics Inc RMCF0805JT100R 0805_HV Fitted 1 R10 4 R11, R14, R15, R16 RES, 10k ohm, 5%, 0.25W, 1206 Vishay-Dale CRCW120610K0JNEA 1206 Fitted 1 R12 RES, 2.00k ohm, 1%, 0.125W, 0805 Panasonic ERJ-6ENF2001V 0805_HV Fitted 1 R13 RES, 220 ohm, 5%, 0.75W, 2010 Vishay-Dale CRCW2010220RJNEF 2010 Fitted 2 R18, R25 RES, 10 ohm, 5%, 1W, 2512 Panasonic ERJ-1TYJ100U 2512M Fitted 2 R19, R30 RES, 0 ohm, 5%, 0.1W, 0603 Vishay-Dale CRCW06030000Z0EA 0603 Fitted 1 R20 RES, 0 ohm, 5%, 0.125W, 0805 Vishay-Dale CRCW08050000Z0EA 0805_HV Fitted 1 R21 RES, 10.0 ohm, 1%, 0.1W, 0603 Vishay-Dale CRCW060310R0FKEA 0603 Fitted 1 R22 RES, 0.91 ohm, 1%, 1W, 2010 Bourns CRM2010-FX-R910ELF 2010 Fitted 1 R23 RES, 1.0k ohm, 5%, 0.1W, 0603 Vishay-Dale CRCW06031K00JNEA 0603 Fitted 1 R24 RES, 100 ohm, 0.1%, 0.125W, 0805 Susumu Co Ltd RG2012P-101-B-T5 0805_HV Fitted RES 30K OHM 1/8W 5% 0805 Stackpole Electronics Inc RMCF0805JT30K0 0805_HV Fitted Stackpole Electronics Inc RMCF0805JT91K0 0805_HV Fitted 1 R26 1 R27 RES 91K OHM 1/8W 5% 0805 1 R28 RES, 36.5k ohm, 1%, 0.1W, 0603 Vishay-Dale CRCW060336K5FKEA 0603 Fitted 1 R29 RES, 511k ohm, 1%, 0.1W, 0603 Yageo America RC0603FR-07511KL 0603 Fitted 1 R31 RES, 44.2k ohm, 1%, 0.1W, 0603 Yageo America RC0603FR-0744K2L 0603 Fitted 16 R32, R34, R36, R37, R39, R40, R42, R43, R45, R47, R48, R49, R50, R51, R52, R53 RES, 470k ohm, 1%, 0.25W, 1206 Yageo America RC1206FR-07470KL 1206 Fitted 6 R33, R35, R38, R41, R44, R46 RES, 2.00Meg ohm, 1%, 0.25W, 1206 Panasonic ERJ-8ENF2004V 1206 Fitted 3 RV1, RV2, RV3 VARISTOR 1080V 10KA DISC 20MM Littelfuse Inc TMOV20RP750E VAR_TMOV20RP750E Fitted 1 T1 Transformer, TH Wurth Elektronik 750342585 XFORMER_ETD29 Fitted 1 U1 IC REG CTRLR FLYBK ISO 7SOIC Texas Instruments UCC28711D D0007A_N Fitted U2 3V Under Voltage Detector, 5-pin SC-70, PbFree Texas Instruments LMS33460MG/NOPB MAA05A_N Fitted 1 TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives Copyright © 2014, Texas Instruments Incorporated 33 Design Files 8.3 www.ti.com Layer Plots To download the layer plots, see the design files at TIDA-00173. Figure 48. Top Overlay Figure 49. Top Solder Figure 50. Top Layer 34 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback Copyright © 2014, Texas Instruments Incorporated Design Files www.ti.com Figure 51. Bottom Overlay Figure 52. Bottom Solder Figure 53. Bottom Layer TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives Copyright © 2014, Texas Instruments Incorporated 35 Design Files www.ti.com Figure 54. Drill Drawing Figure 55. Multilayer Composite 36 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback Copyright © 2014, Texas Instruments Incorporated Design Files www.ti.com 8.4 Altium Project To download the Altium project files, see the design files at TIDA-00173. 8.5 Gerber Files To download the Gerber files, see the design files at TIDA-00173 9 References 1. UCC28700 data sheet, 5-W USB Fly-back Design Review/Application Report (SLUA653) 2. UCC28711 data sheet, Constant-Voltage, Constant-Current Controller with Primary-Side Regulation (SLUSB86) 3. LMS33460 data sheet, LMS33460 3V Under Voltage Detector (SNVS158) 4. MOSFET STF2N95K5 data sheet, N-channel 950 V, 4.2 Ω typ., 2 A Zener-protected SuperMESH™ 5 Power MOSFETs in DPAK, TO-220FP, TO-220 and IPAK packages (www.mouser.com) TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives Copyright © 2014, Texas Instruments Incorporated 37 About the Author 10 www.ti.com About the Author SALIL CHELLAPPAN is a Lead Engineer, Member, and Group Technical Staff at Texas Instruments, where he is responsible for developing customized power solutions as part of the Power Design Services group. Salil brings to this role his extensive experience in power electronics, power conversion, EMI/EMC, power and signal integrity, and analog circuits design spanning many high-profile organizations. Salil holds a Bachelor of Technology degree from the University of Kerala. N. NAVANEETH KUMAR is a Systems Architect at Texas Instruments, where he is responsible for developing subsystem solutions for motor controls within Industrial Systems. N. Navaneeth brings to this role his extensive experience in power electronics, EMC, analog and mixed signal designs. He has system-level product design experience in drives, solar inverters, UPS, and protection relays. N. Navaneeth earned his Bachelor of Electronics and Communication Engineering from Bharathiar University, India and his Master of Science in Electronic Product Development from Bolton University, UK. 38 400- to 690-V AC Input 50-W Flyback Isolated Power Supply Reference Design for Motor Drives TIDU412A – September 2014 – Revised November 2014 Submit Documentation Feedback Copyright © 2014, Texas Instruments Incorporated IMPORTANT NOTICE FOR TI REFERENCE DESIGNS Texas Instruments Incorporated ("TI") reference designs are solely intended to assist designers (“Buyers”) who are developing systems that incorporate TI semiconductor products (also referred to herein as “components”). Buyer understands and agrees that Buyer remains responsible for using its independent analysis, evaluation and judgment in designing Buyer’s systems and products. TI reference designs have been created using standard laboratory conditions and engineering practices. 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